The Flaw in the Calculations
by Grac3
Summary: Part ten of the Loki and the Doctor series (final part). When the Doctor told Loki to live his life out, he certainly didn't mean by impersonating Odin. With a new lease of life that he didn't know he would get, the Doctor has finally had enough of Loki's shenanigans. Episode tag: (immediately) post-Dark World / post-Hell Bent.


**Spoilers for: Hell Bent (seriously, if you haven't seen series 9 of Doctor Who, be warned of major spoilers)**

 **Disclaimer: Don't own Doctor Who or Thor**

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"No… thank _you_."

He almost expected Thor to turn around at his words; to have heard the voice of his supposedly dead brother from the throne.

Yet he didn't: the god of thunder walked out of the ridiculously large hall and the doors swung closed behind him.

Loki took a deep breath and looked out over the empty hall.

His smirk grew, only to falter when a cloud clapping filled the room from his right.

Loki looked over in that direction. At first, he could see no one, but then a figure emerged from behind one of the pillars: a tall man with grey hair. He continued to clap as he made his way to the centre of the room, illuminated clearly in the column of light that spread across the floor.

The man was wearing dark clothing, though the lining of his jacket was a sharp flash of red. He wore a white shirt buttoned up to the top, but he wore no tie. Upon his feet were thick shoes with thick soles. And upon his lined face was a sour look.

"Oh, well done! You managed to pull off the greatest trick of all time and space. They say I dress like a magician, but you actually are one!"

The man lowered his hands to his sides, balling them into fists. He leaned forward slightly to glare at Loki from where he stood in the centre of the room, his thick eyebrows furrowed.

Loki clenched his jaw and tightened his grip around Gungnir. He stood, readying his magic to strike this man down where he stood.

"And who are you?"

The man straightened himself up. "Oh, that's right, you probably don't recognise me. Didn't see this face when you were a child. Well, to be honest, I didn't think _I'd_ see another face. That's what I told you last time I saw you, isn't it? That you'd never see me again."

Loki quieted his magic.

He lowered Gungnir to his side.

He almost took a step back.

"Doctor?"

"A prize for the lad!" the Doctor exclaimed, gesturing towards Loki with an outstretched hand.

Anger flared within Loki, but it soon died, to be replaced with disappointment.

"You lied to me."

The Doctor lowered his hand. "I did no such thing. When I said what I said to you, I believed that it was the truth. I was wrong. I am big enough to admit that. Are you?"

"What do you mean? Where have I gone wrong?"

The Doctor chuckled, holding his arms out wide and gesturing at the scene before him. "Look at yourself. Sitting on your father's throne-"

Loki held Gungnir out threateningly towards the Doctor. "He is _not_ my father!"

" _Odin's_ throne, then!" The Doctor threw his arms up in frustration. "I brought you back to life. I gave you a second chance, and I told you to _do something_ with it! And this is what you choose? To steal a throne that you never wanted in the first place, to fall back under Thanos' control?"

"I have not seen Thanos since I left the Sanctuary-"

The Doctor ran up to him, in a burst of speed Loki had never seen the Time Lord capable of. "But he's still up here, isn't he?" the Doctor pointed to Loki's head, poking him in the temple. Loki sneered and moved his head back, but the Doctor only lowered his hand. Now that the Time Lord was closer, his angry face was all the more intimidating.

"The Mind Stone still works within the mind of Loki, no matter how hard I tried to get rid of it. It's only a fraction that remains, though, and you still chose to give in to that fraction."

"I didn't know what else to do-"

"Anything!"

Loki jumped at the Doctor's raised voice.

"You could have done anything but this! Why are you here? What is it you want?"

A moment passed in silence, and the Doctor grew impatient of waiting for an answer.

"Cause it's not this, is it? It's never been this, not when you were in control. I remember that kid in that library, wanting nothing more than to read books and get away from training. You said it yourself, that you never wanted the throne. Even when you were on it, when Thor was on Earth, and Odin was asleep…"

The Doctor stopped abruptly, looking around himself. "Where is Odin?"

That was a question that Loki did have an answer to.

"Asleep," he said. "Asgard is without an heir, since Thor won't take the throne, without a king, since Odin is asleep, and without a queen, since Frigga is…" he paused, cleared his throat, and continued, "And so it is up to me, the bastard son of Laufey, to take on this burden."

"It is not up to you." The Doctor pointed an accusing and disciplinary finger at Loki. "There are other options."

Loki snorted. "And what might they be?"

"I may know of a connection a certain warrior has to the throne of Asgard that gives her a greater claim to the throne than you ever had."

Loki balked. "'Her'? Sif?"

The Doctor shrugged. "It was River's doing. She did it so we could find out where you were when you were lying dead on Svartalfheim. You're welcome, by the way. Now, back to my original point.

"Question: what are you doing here? Answer: you don't know. Question: why are you staying here if you don't have a reason to, and there's someone else to take the place that you don't even want?"

Loki scoffed. "Where will I go?"

The Doctor's expression darkened. "Anywhere. Anywhere but here. Go wait in the TARDIS, I can get Sif on the throne, we can inform the people of Asgard what has befallen their king, and you can leave and get on with your life – a new life – anywhere in time and space that you so desire."

"Time?" Loki asked, reluctantly allowing himself to feel hopeful.

"I don't see why not."

"You always said that there were things I needed to be around for. That I needed to be in a certain place in order to take my place within the drama of the universe."

The Doctor winced. "I didn't really say it like that, did I? Do me a favour: if I ever say something that poncey again, just hit me, will you? Besides, I've begun to realise that I can take you out of your time if you want me to, just as long as I get you back in time for dinner."

Loki's heart fluttered, though it was not a pleasant feeling. "And what's going to happen at dinner?"

The Doctor said nothing. He just turned away and walked towards the pillar from behind which he had emerged.

Loki didn't make a move to follow him, which the Doctor seemed to notice when he was halfway across the room. He turned back to Loki, one of his eyebrows raised.

"Are you coming or not? I mean, you can always stay here and play king when we both know you hate it; I mean, if you really want to."

Loki grit his teeth, making a show of not wanting to move just yet, though his mind had already been made up. He waited for the Doctor to disappear back into the shadows before he began to follow.

As he had suspected, the TARDIS was waiting for them, hidden just out of sight.

"How long have you been here?"

"Got here just before Thor arrived. Heard that entire exchange. You are good at pretending to be someone you're not."

The Doctor pushed the door of the time ship open and wandered inside. Loki followed.

Once again, the inside of the TARDIS looked vastly different than the last time Loki had been inside. It was dark and dim, covered in metal and Gallifreyan markings. The walls had hexagonal shapes on them. There was a staircase on the far side of the control room leading up to a balcony overhead that had several bookcases on it.

The difference that struck him the most, however, was that there were boards set up around the room: black boards on wooden frames, covered in calculations written in white. They appeared complicated and convoluted, and Loki found himself drawn to them.

"What are these?" Loki asked, looking over his shoulder, but the Doctor was heading towards the door again. "Doctor?"

"Make yourself at home, I'm going to give our dear friend Lady Sif the good news." With a grin, the Doctor sauntered out of the TARDIS and closed the door behind him. Loki didn't need to go up and check it to know that it had been locked from the outside.

Scowling, he turned back to the black board before him, running his eyes hungrily over the calculations. They truly were a thrilling sight to behold. Loki wondered how long the Doctor had been working on this particular problem – if he had even been working at all, or if what he saw before him were just doodles. It wasn't something he could have imagined any of the other versions of the Doctor doing; yet this one seemed more scholarly, more scientific.

More interesting.

Which made it all the more laughable when Loki spotted a mistake right in the most integral part of the equation. Double checking to see whether or not he was mistaken himself, Loki reached for the chalk sitting on a wooden perch at the bottom of the black board's frame and edited the equation. His dainty handwriting looked rather out of place and entirely conspicuous in amidst the Doctor's unruly scrawls, but at least now the equation flowed correctly.

He had just placed the chalk back down on the perch when the Doctor burst back into the TARDIS with a triumphant look on his face. He strode straight over to the control panel and set the ship in flight.

When the ship was safely in the air, the Doctor leaped up the stairs and retrieved a strange stringed instrument that he flung over his shoulder, and slipped a pair of dark glasses over his eyes. He plucked at the instrument's strings, and a loud noise filled the ship.

"So, Sif is safely on the throne of Asgard, or she's getting there at least, and you can go anywhere you want. Where do you wanna set yourself up? You've got the whole universe." As he spoke, the Doctor plucked at the strings of his instrument, creating an electronic tune that filled the control room.

Loki was about to speak, when the Doctor abruptly stopped playing his music. He was glaring in Loki's direction.

"Doctor?"

The Doctor ripped the glasses off of his face and threw them on the floor at the top of the stairs to the balcony. Flying down the staircase, taking the steps two at a time, the Doctor stood next to Loki, devouring the calculations on the board.

"What is that?" the Doctor pointed an accusatory finger at the change that Loki had made.

"Your calculation was wrong. I fixed it."

"What are you talking about, wrong? I'm never wrong, I'm the Doctor, and 'doctor' means 'never wrong'-"

"Does anyone actually believe the things you say?"

The Doctor ignored him, placing a hand on his shoulder and all but pushing him out of the way as he turned towards the calculations. He stepped closer to the black board, almost pressing his nose against them and smudging the white as he examined Loki's correction.

His eyes widened.

He stepped back from the board and turned to Loki with something akin to wonder in his eyes. "Since when have you been an expert in thermonuclear astrophysics?"

Loki shrugged, an air of false modesty controlling his features. "I may have studied magic most of the time, but magic is nothing more than science. At its most basic level, magic is… Well…" He waved a hand at the board.

The Doctor blinked at the board, then at Loki, then at the board again. "This… is simple to you?"

"Well, yes," Loki said matter-of-factly, taking great satisfaction in the look of indignation on the Doctor's face. "Very simple indeed."

The Doctor took the strange instrument off his shoulder, placing it very carefully against the leg of the structure holding the board in place. He straightened up and placed both of his hands on Loki's shoulders.

"Loki, I am about to ask you something monumental. You should feel proud and honoured to be asked this question. Are you ready for it?"

Loki sneered, and the Doctor took it as confirmation.

"Do you want to travel with me?"

Loki faltered. "Travel with you?"

"Yes, like Jo and Sarah and Rose and Jack and Amy and Rory and River."

"And Clara."

The Doctor's brow furrowed. "Clara who?"

Loki didn't have time to voice his confusion at that statement.

"Never mind, the question is: yes or no? Will you come with me to see all of time and space?"

Loki opened his mouth to answer, readying the answer that he would have given to that question ever since he had been preparing for Thor's coronation all that time ago.

But he stopped himself. It was worthless trying to convince the Doctor that he still wanted the throne of Asgard. After all, he could have called the guards back when the Doctor had first shown himself, or when he had been talking about Sif's rightful claim to the throne. He could have easily replaced the glamour disguising himself as Odin and got rid of the Doctor, safeguarding his place on the throne that he had wanted for so long.

But he hadn't. Because he didn't want the throne. He never had. Isn't that what he had told Thor while the Bifrost had been tearing Jötunheim apart? Indeed, isn't that what had driven him to compromise Thor's coronation in the first place so that the throne would remain Odin's until Thor was ready to take it himself? Kingship had never been a part of Loki's plan…

But without that, what did he have? Where could he go? The Doctor had let him loose on his own once, and he hadn't known what to do; he had merely slipped back into his old ways. He needed a change of scenery. He needed to get away from Asgard, from the Mind Stone's influence. He needed…

He needed a Doctor.

Loki nodded. "I will, Doctor." Despite himself, Loki couldn't help the tug at the corner of his lips. He felt a strange feeling bubbling up inside his chest. He didn't dare to name it, but he couldn't help but think – in the very back of his brain – that it was happiness.

The Doctor grinned at him, releasing Loki's shoulders and picking up his instrument again. A wide smile grew on his face, reaching his eyes. It was the happiest Loki had ever seen the Doctor.

The Doctor strummed the strings again. "Oh, Loki, you and I are gonna have so much fun. And don't worry; I'll get you back in time for dinner."

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 **A.N.:** This series is officially finished! I have left it open for the possibility of a sequel, though I have no idea when/if that will happen, as I currently have no ideas for any further stories. Thank you to everyone who got this far and carried on reading. As I promised all the way back when I posted Prelude, I will be adding to my profile the order in which these stories appear from the Doctor's POV if you're interested. Again, thank you for reading!


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